The invention relates preferably, but not exclusively to cannister rotation mechanisms for a cannister into which a fiber ribbon is fed, which after being completely filled is then transported to an open-ended spinning machine, where the fiber ribbon is drawn out of the cannister and spun into a thread. The cannisters are normally placed under the spinning mechanism of the open-ended spinning machine and cannot, therefore, have a very great height. In order, therefore, to increase the full-weight of fiber ribbon in such a cannister, so that cannister replacement is not necessary as often, it is known to maintain the fiber ribbon roll, which is formed between the turntable and the cannister bottom during feed-in, under pressure by a controlled, slow, downward movement of the movable cannister bottom, so that fiber in the cannister is compressed and a correspondingly greater fiber ribbon weight can be fed into the cannister.
A known cannister rotation mechanism (DT-OS 1 953 988) demonstrates a stroke device for the controlled lowering of the movable cannister bottom. This device contains a Nurnberger shear, also known as a pantograph, which rotates synchronously with the cannister. The necessary drive of the pantograph, however, is extraordinarily complicated and expensive and its stroke speed can only be adjusted with difficulty. This cannister rotation mechanism requires, in addition, a substantial vertical height, so that it is not possible, at least under normal conditions, to place it up on the floor of the machinery room beneath the turntable, but it must instead be partially sunk into the floor, which has tremendous disadvantages. In order to build the stroke device structurally simpler, it is known to make it in the form of a stroke-cylinder unit, which is arranged vertically and whose stroke rod raises and lowers the movable cannister bottom. This necessitates, however, a long vertical cylinder, which has such great structural height that the cylinder also must be installed below the floor of the machinery room which again is extremely undesirable.